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noun

oxidation

ok-sih-DAY-shun

Oxidation (noun) means a chemical reaction in which a substance loses electrons; in everyday terms, the reaction of a material with oxygen, as when iron rusts or a cut apple browns. Example: “Oxidation turns the exposed metal a dull orange within days.”

noun
1
A chemical reaction in which a substance loses electrons; in everyday terms, the reaction of a material with oxygen, as when iron rusts or a cut apple browns.
"Oxidation turns the exposed metal a dull orange within days."
"A squeeze of lemon slows the oxidation of the avocado."
2
In food, drink and cosmetics, the deterioration of a product through contact with air, changing its colour, smell or taste.
"The wine had suffered oxidation and tasted flat and nutty."
"Vitamin C serums are packaged in dark bottles to limit oxidation."

How to use oxidation

Learner’s notes

In plain EnglishWhat happens when something reacts with the air, like metal rusting or fruit browning.

When to use it

Technical in chemistry, but everyday in cooking, wine and skincare contexts.

Memory tip

'Oxidation state' is a bookkeeping number for electrons, not a description of how oxidised something looks.

Trace the full origin ↓
Easily confused with
Common pairings
prevent oxidation oxidation state oxidation and reduction signs of oxidation
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Test yourself on “oxidation” A quick quiz — meaning, synonyms & usage

Fill the gap

Can you complete this real example?

_____ turns the exposed metal a dull orange within days.

Etymology

From oxide, coined in French from Greek oxys 'sharp, acid' and the ending of acide, plus the noun ending -ation. Oxygen was originally named as the supposed acid-forming element.

Origin: French

Related words

Rhymes for oxidation

See all rhymes for oxidation →

Frequently asked questions

What is the difference between oxidation and reduction?

Oxidation is the loss of electrons and reduction is the gain of them. They always happen together, since the electrons one substance loses another must gain, which is why the pair is called a redox reaction. The mnemonic is OIL RIG: oxidation is loss, reduction is gain.

Does oxidation always involve oxygen?

No. Oxygen is the commonest oxidising agent and gave the process its name, but the modern definition is purely about losing electrons. Iron reacting with chlorine is oxidation with no oxygen present at all.

Why do cut apples go brown?

Enzymes in the flesh react with oxygen in the air and produce brown pigments. Acid such as lemon juice slows the enzyme, and so does keeping the surface away from air with water or wrapping.

What is the meaning of oxidation?

"oxidation" (noun) means a chemical reaction in which a substance loses electrons; in everyday terms, the reaction of a material with oxygen, as when iron rusts or a cut apple browns.

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Definitions: FreeDict original editorial · etymology from FreeDict original editorial